1. Field of the Invention
The present invention relates to a vacuum circuit breaker, and more particularly to an improved terminal connection locking apparatus for a vacuum circuit breaker capable of facilitating a terminal connection locking operation and obtaining a safety with regard to the manipulation for preventing a terminal disconnection of the circuit breaker when it is in a conductive state.
2. Description of the Background Art
In general, a vacuum circuit breaker incorporates an apparatus for connecting or disconnecting a power source to an electrical load in a high voltage distributing power line through which there flows a high voltage current in thousands of volts and hundreds of amperes. In order to effectively shield an arc which occurs during a switching operation, the vacuum circuit breaker is provided with a vacuum chamber having a switching mechanism therein.
As shown in FIGS. 1 and 2, the general vacuum circuit breaker is generally composed of switching mechanism 10, switching actuator 20 for actuating the switching mechanism 10, and an auxiliary device (not shown).
With reference to FIGS. 3 and 4, the switching mechanism 10, the switching actuator 20 and the auxiliary device (not shown) will be described in further detail.
The switching mechanism 10 is directed to connect or disconnect an electrical connection of the power source and electrical load and disposed in the vacuum chamber 11.
A movable contactor (not shown) of the switching mechanism 10 is operable in connection with the switching actuator 20 of the vacuum circuit breaker, and when the vacuum circuit breaker is in a turn-on state, the movable contactor (not shown) remains in contact with a fixed contactor (not shown) of the switching mechanism 10.
Also, when the circuit breaker is in a turn-off state, the movable contactor (not shown) is separated from the fixed contactor by an appropriate breaking distance at an appropriate speed.
The switching actuator 20 which denotes an entire operational apparatus provided in a front part of the switching actuator 20 serves as an mechanical mechanism for carrying out a turn-on/off contact operation of the switching mechanism 10.
The auxiliary device for allowing the circuit breaker to become in normal operation, includes: a control apparatus (not shown) provided together with the switching actuator 20, receiving an externally generated electrical signal and controlling the on/off operation of the circuit breaker; a terminal connection device for enabling a moving on/off operation of the circuit breaker; and an interlock device for protecting the terminal connection device.
The thusly constituted conventional terminal connection locking apparatus will now be explained.
As shown in FIG. 5, the switching mechanism 10 moves from driving position to test position in a moving-off operation, and from test position to driving position in a moving-on operation.
The test position denotes a location wherein it is possible to turn on/off the vacuum circuit breaker in a case in which the input and output terminals 12a, 12b are separated from power source and load terminals 13a, 13b, that is, when current does not flow in the circuit breaker. The driving position indicates a location wherein the current does flow when the circuit breaker is turned on and the current does not flow when the circuit breaker is turned off in a case in which the input and output terminals 12a, 12b are in contact with the power source and load terminals 13a, 13b.
As further shown in FIGS. 3 and 4, a cam shaft 30 is disposed in the switching actuator 20 and a stopper 31 is engaged to an end portion of the cam shaft 30.
A lower end portion of a support rod 33 is fixed to a base plate 40 of the switching actuator 20, and a higher end portion of the support rod 33 is extended outside the vacuum circuit breaker to form a handle 32.
The handle 32 of the support rod 33 is covered with a handle cover 34.
Also, to a lower side portion of the support rod 33 there is coupled an L-type hook 35. A shielding plate 37 engaged to a fixed plate 36 is connected to another lower side portion of the support rod 33.
The shielding plate 37 is provided to move up and down by manipulating the handle 32 to open or close a contact control screw 38.
The stopper 31 rotates forwardly or backwardly in accordance with a turn-on/off operation of the circuit breaker, and the stopper 31 is mounted on or deviated from an upper portion of the L-type hook 35, thereby controlling an upward movement of the L-type hook 35.
Reference numeral 50 denotes wheels for moving the circuit breaker.
The operation of the thusly constituted conventional terminal connection locking apparatus for a vacuum circuit breaker will now be described.
Initially, the control apparatus (not shown) allows the circuit breaker to be turned on and the cam shaft 30 to rotate in an anti-clockwise direction in accordance with an electrical signal, and accordingly the stopper 31 engaged to the cam shaft 30 rotates in an anti-clockwise direction in order for the stopper to be in contact with the upper portion of the L-type hook 35.
Here, when the handle 32 is upwardly pulled, the L-type hook 35 engaged to the support rod 33 is hooked on the stopper 31, whereby the support rod 33 is not allowed to further move to an upward direction.
Subsequently, the shielding plate 37 connected to the support rod 33 is also not allowed to upwardly move, and the contact control screw 38 becomes inoperable, thereby preventing the terminal separation of the circuit breaker.
Meanwhile, when the circuit breaker is turned off by the control apparatus, the cam shaft 30 is rotated in a clockwise direction, and also the stopper 31 engaged to the cam shaft 30 is also rotated in the clockwise direction, whereby the stopper 31 is deviated from the upper portion of the L-type hook 35. Here, when the handle 32 is upwardly pulled, the L-type hook 35 connected to the support rod 33 is not hooked on the stopper 31, whereby the support rod 33 becomes upwardly movable.
Accordingly, the shielding plate 37 connected to the support rod 33 is also moved to an upward direction, thereby exposing the contact control screw 38.
Then, the exposed contact control screw 38 guides the circuit breaker to move off by use of a control handle (not shown) which is to be inserted into the contact control screw 38.
However, when the circuit breaker remains in a turn-on state, the control handle (not shown) is placed on the contact control screw 38 of the circuit breaker. Also, when the circuit breaker is located in the driving position, if the circuit breaker remains turned on, an electrical shock may incurred to the manipulator.
Therefore, there is strongly required a terminal connection locking apparatus which does not allow the control handle (not shown) to be covered onto the contact control screw 38 when the circuit breaker remains turned on.
However, the conventional terminal connection locking apparatus for a vacuum circuit breaker according to the present invention is provided with a spaced distance between the handle and the contact control screw, thereby generating difficulties in working, manipulation, and safe operation.